Make . Make sure you use lots of lubricant. Also, you can buy vaginal dilators if the experience is too painful, or you want to prepare yourself prior to the first encounter. Vaginal dilators are plastic cylinders that are used to treat many vaginal conditions where the introitus (opening of the vagina) are very tight. The purpose is to slowly stretch the area over time by slowly increasing the size of the dilator, all without pain.
Lastly, remeber to use condoms; std's (sexually transmitted diseases) are also something you should consider.
Be careful and have fun!